Spontaneous Intracranial Hypotension
Authors: YUTAKA OZAKI, YUKIHARU SUMI, SHINSUKE KYOGOKU, NOBORU SHINDOH, HITOSHI KATAYAMA
Journal: Clinical Nuclear Medicine (1999)

The authors describe two patients with spontaneous intracranial hypotension. The patients had the cardinal features of a postural headache. In both patients, radionuclide cisternography revealed cerebrospinal fluid (CSF) leakage at the cervicothoracic junction and early accumulation of isotope in the urinary tract. Postmyelography CT scans showed no underlying structural abnormalities. Both patients were treated successfully by intravenous infusion of low-osmolarity fluid. Radionuclide cisternography obtained after treatment in one of the patients showed that the CSF leak had disappeared. Radionuclide cisternography enabled the causes of spontaneous intracranial hypotension to be differentiated and visualized the sites of CSF leakage. It was also useful for evaluating changes in a CSF leak after treatment. FIGURE 1Fig. 1: A 32-year-old woman had a 4-week history of persistent headache. She had no relevant medical history, such as head injury or lumbar puncture. She underwent lumbar puncture and the opening pressure was not measurable. Spontaneous intracranial headache was suspected and radionuclide cisternography was performed with lumbar (L4–L5) intrathecal instillation of 18.5 MBq (0.5 mCi) In-111 DTPA. Radionuclide cisternograms obtained (A) 3 and (B) 24 hours after In-111 DTPA injection showed bilateral CSF leakage at the level of the cervicothoracic junction (arrows) and early accumulation of the isotope in the kidneys (arrowheads). (C) Spot cranial images obtained 24 hours after In-111 DTPA injection showed poor migration of the isotope over the cerebral convexities. The patient underwent intravenous infusion of low-osmolarity fluid, her headache resolved, and her CSF pressure increased to within the normal range. She was discharged without complication and has remained free of problems during follow-up for 3 years.FIGURE 2Fig. 2: Severe headache developed in a 29-year-old woman that was relieved by lying flat. She had no relevant previous medical history. A lumbar puncture resulted in a dry tap. She underwent intravenous infusion of low-osmolarity fluid after admission and her headache resolved 3 days later. Radionuclide cisternography was performed, as described for patient 1 in Figure 1. Spot cranial cisternograms obtained (A) 3 and (B) 24 hours after In-111 DTPA injection showed left-sided extrathecal abnormal uptake of the isotope (arrows) at the cervicothoracic junction and reduced isotope passage over the convexities. (C) Spot pelvic imaging obtained 6 hours after In-111 DTPA injection showed early accumulation of the isotope in the bladder (arrowheads). One month later, a second radionuclide cisternography was performed. (D) A spot cranial cisternogram obtained 3 hours after In-111 DTPA injection showed that the CSF leak had disappeared and intracranial radionuclide passage was increased. She was discharged without complication. The characteristic radionuclide cisternographic features of this syndrome have been described (1–5). In most cases, radionuclide cisternography shows early accumulation of isotope in the bladder, indicating rapid uptake of the isotope into the bloodstream. This abnormal pattern, however, does not necessarily distinguish a CSF leak from CSF hyperabsorption. If a leak is present, the concentration of isotope at the site of the leak increases progressively and the passage of isotope from the basal cisterns to the sylvian fissure and interhemispheric cistern is reduced, consistent with a low CSF pressure state. If spontaneous intracranial hypotension is caused by reduced cerebrospinal fluid production, then cisternography would probably show slow egress of the isotope and a high concentration remaining for a prolonged period at the injection site. The diagnosis of spontaneous intracranial hypotension is made based on the clinical symptoms and lumbar puncture findings. Once the diagnosis has been confirmed by lumbar puncture, further investigation is necessary to determine a possible cause. Radionuclide cisternography is useful in this situation, because it can differentiate the causes of this syndrome and visualize the sites of CSF leak.